1. Field of the Invention
The present invention relates to a cooking appliance, such as a microwave oven or electric oven, having the function of weighing heating loads.
2. Description of the Prior Art
In a conventional microwave oven, for example, when food, which is a heating load, is heated by microwaves, most of the high frequency energy is absorbed by the food, unlike the case of using a conventional heat source. Thus, since the time needed for heating greatly increases with the weight of food, it is very difficult to set the optimum cooking time and particularly where defrosting is intended, if the food is heated for a longer time than the optimum time, this can result in raw meat being boiled.
From such viewpoint, there have been proposed many microwave ovens equipped with weighing means and a microwave output control operatively connected to said means.
In reality, however, such weighing function-equipped microwave ovens have not been put into practical use.
A first reason is a problem about the position of the load receiving pan for carrying food thereon. That is, measurements of the weight of food require a sufficient space around the load receiving pan to allow the food to be placed thereon.
From this viewpoint it may be contemplated, as the simplest construction, to install a load receiving pan on the upper surface of the microwave oven body and install a measuring device within the body for detecting the weight of food in operative association with the movement of the load receiving pan. When the general conditions for use of cooking appliances such as microwave ovens are considered, however, it will be seen that the upper surface of the body would be utilized to place things thereon or would be close to the ceiling or hanger shelves or located at too high a place to reach it; thus, this is inconvenient for use.
Another idea would be to provide a construction wherein the turntable in the heating chamber of the microwave oven body is concurrently used as a load receiving pan while installing a weighing device operatively connected to the turntable. However, such a construction will encounter technical difficulties and involve high costs. Even if this construction is somehow obtained, it is necessary to subtract the weight of a container, wrapper, etc. for food, that is, to allow for the tare, thus requiring additional operation of first weighing the container and then putting the food therein and reweighing the same. This construction, dictating such additional operation to be performed in the narrow heating chamber, cannot be said to be convenient for use.